A subject information acquisition apparatus (photoacoustic apparatus) developed to detect breast cancer is described in Non-Patent Literature 1 (NPL 1). In the apparatus described in NPL 1, a subject (a breast) is compressed between a glass plate and an acoustic wave probe, whereupon the breast is irradiated with illumination light (near-infrared light) using an Nd:YAG laser as a light source through the glass plate. An acoustic wave generated in the interior of the subject (the breast) is received by the acoustic wave probe, whereupon internal tissue of the subject (the breast), and in particular breast cancer angiogenesis, is reconstructed as an image and displayed.
With the apparatus of NPL 1, however, a gap may form between a part of the subject (the breast) and the acoustic wave probe, leading to lifting. The lifted part contains air, causing dramatic differences in acoustic impedance, and since the acoustic wave cannot pass through the lifted part, there results a region that cannot be subjected to image reconstruction.
Patent Literature (PTL) 1, 2 and 3 disclose methods for dealing with this type of lifting.
FIG. 5A shows an outline of PTL 1, in which an acoustic matching agent is filled between two compression plates for compressing a subject. FIG. 5B shows an outline of PTL 2. PTL 2 discloses a compression plate constituted by two plates for compressing a subject, an acoustic wave probe, and a flexible container for realizing acoustic matching. FIG. 5C shows an outline of PTL 3. PTL 3 similarly discloses a compression plate constituted by two plates and a gel pad provided between the two plates.